Thursday, January 3, 2013

New paper finds another mechanism by which the Sun controls climate

A paper published today in Geophysical Research Letters finds that short-term changes in solar activity over the 11 year solar cycle have a significant influence on the North Atlantic Oscillation [NAO] and Arctic Oscillation [AO]. According to the authors, "Variability in solar irradiance has been connected to changes in surface climate in the North Atlantic through both observational and climate modelling studies." Using new satellite data demonstrating that solar UV varies by a factor that is 4 to 6 times larger than typical previous estimates, the authors find a mechanism to explain the solar effect on these climate oscillations via increased production of ozone in the atmosphere. The authors conclude that these large changes in solar UV can have amplified effects on regional climate and may be useful for predicting seasonal and long term climate change in Europe.Slides from a presentation on this paper by one of the authors:

Abstract: Variability in solar irradiance has been connected to changes in surface climate in the North Atlantic through both observational and climate modelling studies which suggest a response in the atmospheric circulation that resembles the North Atlantic Oscillation or its hemispheric equivalent the Arctic Oscillation. It has also been noted that this response appears to follow the changes in solar irradiance by a few years, depending on the exact indicator of solar variability. Here we propose and test a mechanism for this lag based on the known impact of atmospheric circulation on the Atlantic Ocean, the extended memory of ocean heat content anomalies and their subsequent feedback onto the atmosphere. We use results from climate model experiments to develop a simple model for the relationship between solar variability and North Atlantic climate.